The British and Irish prime ministers arrived in Northern Ireland Friday to formally announce a breakthrough agreement that saves the province's peacemaking coalition of Catholics and Protestants.

Gordon Brown and his Irish counterpart Brian Cowen went to Belfast after the Democratic Unionists, the region's main Protestant party, reached an agreement with Sinn Fein, the major Irish Catholic party, on transferring policing and judiciary powers from London to Belfast.

The prime ministers are expected to unveil details of the agreement Friday.

Sinn Fein had threatened to quit the power-sharing government during nearly two weeks of talks with the Protestants, who wanted guarantees that they would not be restricted from holding parades celebrating 17th century battle victories. Some of those parades pass through Catholic neighborhoods, which the Catholics call a deliberate provocation.